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- What we treat - [Read](https://www.manual.co/blog) - [About](https://www.manual.co/about) - [Login](https://www.manual.co/login?redirect=%2Faccount/home)   # Filters Show 0 Results  What we treat Hair Loss Treatment  Testosterone Replacement  Erectile Dysfunction  Account [Login ](https://www.manual.co/login?redirect=%2Faccount%2Fhome) Support [Help Centre ](https://help.manual.co/hc/en-us) Learn [Health Centre by Manual ](https://www.manual.co/health-centre) [Guarantee ](https://www.manual.co/pages/guarantee) Explore [Hair loss overview ](https://www.manual.co/hair-loss) Treatments [Complete Hair Loss Plan ](https://www.manual.co/hair-loss/complete-hair-loss-plan) [Finasteride Plan ](https://www.manual.co/hair-loss/finasteride) [Minoxidil Plan ](https://www.manual.co/hair-loss/minoxidil) [Hair Vitamins ](https://www.manual.co/daily-health/hair-vitamins) [Power Shampoo ](https://www.manual.co/hair-loss/power-shampoo) Reviews [What people say (4.5/5 Trustpilot) ](https://www.manual.co/t/hair-loss/reviews) [Hair regrowth gallery ](https://www.manual.co/t/hair-loss/results) Everything you need to know Account [Login ](https://www.manual.co/login?redirect=%2Faccount%2Fhome) Support [Help Centre ](https://help.manual.co/hc/en-us) Learn [Health Centre by Manual ](https://www.manual.co/health-centre) [Guarantee ](https://www.manual.co/pages/guarantee) Explore [Testosterone replacement overview ](https://trt.manual.co/) About TRT [How it works (pricing) ](https://trt.manual.co/how-it-works) Check your testosterone levels Supplements [Testosterone Support ](https://www.manual.co/testosterone-replacement-therapy/testosterone) Reviews [What people say (4.5/5 Trustpilot) ](https://www.manual.co/t/testosterone-replacement-therapy/reviews) Everything you need to know Account [Login ](https://www.manual.co/login?redirect=%2Faccount%2Fhome) Support [Help Centre ](https://help.manual.co/hc/en-us) Learn [Health Centre by Manual ](https://www.manual.co/health-centre) [Guarantee ](https://www.manual.co/pages/guarantee) Explore [Erectile dysfunction overview ](https://www.manual.co/erectile-dysfunction) Treatments [Sildenafil Plans ](https://www.manual.co/erectile-dysfunction/sex-health-treatment#SILDENAFIL) [Tadalafil Plans ](https://www.manual.co/erectile-dysfunction/sex-health-treatment#TADALAFIL) [Viagra Plans ](https://www.manual.co/erectile-dysfunction/sex-health-treatment#VIAGRACONNECT) Everything you need to know Account [Login ](https://www.manual.co/login?redirect=%2Faccount%2Fhome) Support [Help Centre ](https://help.manual.co/hc/en-us) Learn [Health Centre by Manual ](https://www.manual.co/health-centre) [Guarantee ](https://www.manual.co/pages/guarantee)  Sleep # Melatonin Side Effects: What to Know  Medically approved by Dr Earim Chaudry Chief Medical Officer Last updated 1st February 2022 #### In 30 seconds Melatonin is a natural hormone made by your body to help control your sleep patterns. It’s commonly prescribed as an artificial medicine for people who have symptoms of insomnia or other sleep problems. [Melatonin](https://www.manual.co/sleep/melatonin-circadin) side effects can include headaches, daytime sleepiness, nausea, dizziness, restlessness, and strange dreams. More seriously, blurry vision, low mood, and confusion can all happen too. Table of contents - Melatonin: Your Body’s Natural... - What is Melatonin? - How Effective is Melatonin for... - Is Melatonin Safe? - Melatonin Side Effects - Who Shouldn’t Take Melatonin? - Alternatives to Melatonin - Key Takeaways - FAQs ## Melatonin: Your Body’s Natural Sleep Aid Melatonin is a short-term treatment for insomnia and other sleep disorders. While it can be bought over the counter in other countries, in the UK at least, melatonin is classed as a prescription medicine. That’s because it can have some serious side effects. As a result, it’s vital to know what they are before you take the treatment. In this post, we share the **melatonin side effects** you need to know. And, while we’re here, we’ll show you some alternatives you might prefer. ## What is Melatonin? Melatonin is a hormone that is produced naturally by your *pineal gland*, a gland in your brain. It is made to help support your natural sleep cycle — essentially by making you feel sleepy at the right time. The hormone’s job is to regulate your sleep-wake cycle, or what’s known as your circadian rhythm — the way that your body responds to patterns of light and dark. When it’s dark, your body naturally produces more melatonin to signal your body to prepare for sleep. And when the sun comes up, and your body experiences more light, less melatonin is produced. As a result, people with sleep problems or who are prone to sleep disruptions [have been found](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3354573/) to have lower levels of melatonin. In the UK, melatonin is sold under the brand name **Circadin**. Usually, you’ll take a 2mg tablet a couple of hours before you go to bed. It’s normally prescribed only for a couple of weeks. 13 weeks is the maximum you can be prescribed melatonin. **Note:** In the US, melatonin is sold as a dietary supplement, so you can buy it without a prescription. In the UK (along with the EU, Canada, Japan, and Australia), melatonin supplements are available *by prescription only*. If someone – or a website – is offering over-the-counter melatonin, it’s crucial that you don’t take it. [You simply cannot be sure what’s in it](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5263069/). ## How Effective is Melatonin for Sleep Aid? [Studies have consistently shown](https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know) that melatonin effectively improves both the time it takes to fall asleep and the quantity of total sleep. Importantly, research found that it was better than a placebo in people of all ages, from children to older adults. Yet, it’s not always effective in every case. People suffering from jet lag or acute sleep disruptions may see a benefit. However, the [effects may not be so significant](https://www.ncbi.nlm.nih.gov/books/NBK11941/) in those with chronic insomnia or other long-term sleep conditions. ## Is Melatonin Safe? Melatonin is a safe medicinal treatment for the management of short-term sleep problems. However, it is a medicine, and that means we can only be sure it’s safe when it’s taken in recommended doses by people who’ve had it prescribed. Melatonin may be prescribed for the following people: - Those over the age of 55 and suffering from short-term sleep problems such as jetlag. - Children struggling to sleep due to neurological disorders such as attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder. In these cases, doctors will want to monitor effects every six months. - People who experience severe headaches. You can use melatonin preventatively – but again, only by prescription. Like all medicines, melatonin is not safe for people who do not have a medical need for it. ## Melatonin Side Effects So, what are the possible side effects of melatonin? There are many *possible* short term side effects. However, the good news is that they are all quite unlikely. For example, [one systematic study](https://pubmed.ncbi.nlm.nih.gov/31722088/) in the UK found that the most common side effect (daytime sleepiness) happened in just 1.66% of cases. Here are the most common side effects you can expect: - Daytime drowsiness or sleepiness - Headache - Stomach ache or nausea - Dizziness - Irritableness and restlessness - Dry mouth - Itchy skin - Nightmares or night sweats All of these are easily managed. Usually, they will resolve themselves without any necessary intervention or will stop after stopping taking the medication. And the more severe side effects? These can include the following: - Sadness or low mood - Blurry vision or watery eyes - Feeling faint or passing out - Confusion or acute vertigo - Continuous bleeding or blood in your urine - Psoriasis These are not common and will be experienced by fewer than one in a thousand people. However, they do happen, and it’s essential to know the risk. If you experience any of the above serious side effects – or if you have difficulty breathing or develop a severe rash – immediately consult a doctor. ## Who Shouldn’t Take Melatonin? Like many drugs, melatonin is not for everyone. This is particularly true for those suffering from – or taking treatment for – other health conditions. If you are taking any of the following medicines, it’s best to check with your doctor before taking melatonin: - Antidepressants - Blood pressure medicines - Blood thinners such as warfarin - Carbamazepine, for the treatment of epilepsy - Oestrogen - Other sleeping pills - ‘Herbal’ remedies to aid sleep Similarly, you should not take melatonin if you are pregnant or breastfeeding or have an allergy to melatonin. ## Alternatives to Melatonin Melatonin is not the only treatment out there to tackle sleep disruptions. As safe, natural alternatives, you could try some of these instead: - **Chamomile** is a flower closely related to the daisy. It’s often made into teas and infusions and has been found to [improve sleep quality](https://pubmed.ncbi.nlm.nih.gov/29154054/) and help you get to sleep. - **Tart cherry** is a fruit known for its sleep benefits. [Studies have shown](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617749/) that it can increase sleep efficiency. You can drink it as a juice or take it in dietary supplements. - **Lemon balm** is a herb that is part of the mint family. It gets its name from its lemony scent and flavour. [Studies in people](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230760/) suffering from anxiety and stress have shown that it can be an incredibly effective tool to encourage healthy sleep. And while it is not a natural remedy, [**promethazine**](https://www.manual.co/sleep/promethazine-phenergan) is another effective sleep aid. It’s commonly found in medicines such as Night Nurse. ## Key Takeaways Melatonin is a medicine prescribed for short-term use in people with acute sleep problems. It has been found to have beneficial effects on sleep quality and sleep time in those who use it. However, melatonin does have side effects. These include daytime sleepiness, headaches, nausea, and faintness — as well as more serious effects like generalised confusion. There are alternatives out there to help you sleep better. A combination of chamomile, tart cherry, and lemon balm has been shown to boost your sleep time and quality. You can find all of these natural ingredients in [Manual’s Good Nights supplements](https://www.manual.co/daily-health/good-nights). ## FAQs ### Why Won’t the FDA Approve Melatonin? In the US, melatonin is approved for use by the Food and Drug Administration (FDA). However, the FDA does not recognise melatonin as a medicine but as a dietary supplement. That means it is less strictly regulated than prescription medicines. As a result, you should always make sure you buy melatonin from a trusted source. ### Why is Melatonin Banned UK? Melatonin is not banned in the UK. Instead, it is available only as prescription medicine. That means it is illegal to sell melatonin if you are not an accredited pharmacy. ### Is It OK to Take One Melatonin Every Night? If your doctor has prescribed melatonin every night, it is okay to do so. However, this will depend on the amount of melatonin prescribed. Typically, medical advice states that you can take a 2mg dose of melatonin every night, or two or three times a week. Importantly, though, long-term safety is not guaranteed. As such, the recommended use of melatonin is limited to a maximum of 13 weeks. ### Can Melatonin Give You Cancer? While we do not know all of the long-term effects of melatonin, there is no evidence that it can give you cancer. In fact, [the science suggests](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5503661/) it can have the opposite effect by controlling the growth and spread of cancerous cells and tumours. While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor. #### [Explore](https://www.manual.co/blog) [ Sleep Your Guide to Using Promethazine for Sleep Promethazine is a drowsy antihistamine that is proven to help insomnia.](https://www.manual.co/blog/your-guide-to-using-promethazine-for-sleep) [ Sleep When to Take CBD Oil for Sleep The research is young, but CBD oil is showing some promising possibilities when it comes to alleviating the symptoms of sleep disorders.](https://www.manual.co/blog/when-to-take-cbd-oil-for-sleep) [ Sleep What Over The Counter Sleeping Pills Can You Get in the UK? There are two ways to get sleeping pills in the UK — by prescription or over the counter.](https://www.manual.co/blog/what-over-the-counter-sleeping-pills-can-you-get-in-the-uk) [ Sleep Your Guide to Sleep Inertia Sleep inertia is the feeling of grogginess, drowsiness, or disorientation you feel immediately after you wake up.](https://www.manual.co/blog/your-guide-to-sleep-inertia) #### Have a question? Whatever it is, get in touch:   [help@manual.co](mailto:help@manual.co)We aim to reply in 24hrs [ Email us](mailto:help@manual.co) We aim to reply in 24hrs Our services are not intended for use in a medical emergency. 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Pharmacies: Manual Pharmacy Superintendent Pharmacist Dawn Neil GPhC Registration: 2063362 Copyright 2026 Manual™. All rights reserved.